Hydrogen sulfide has been removed previously from hydrocarbon gases utilizing iron oxides. U.S. Pat. No. 1,160,375 (Burkheiser) teaches that H.sub.2 S may be removed from hydrocarbon gases containing ammonia by reaction with Fe.sub.2 O.sub.3 and free sulfur. The reaction product, Fe.sub.2 S.sub.3, is unstable in air, regenerating the Fe.sub.2 O.sub.3 and liberating H.sub.2 S which is reacted with ammonia in a second step to produce forms of ammonium sulfide. U.S. Pat. No. 1,734,307 (Sperr) discloses a method of removing hydrogen sulfide by first reacting the H.sub.2 S with an alkali such as sodium carbonate, and further reacting the resulting hydrogen sulfide salt with Fe.sub.2 O.sub.3 to form Fe.sub.2 S.sub.3. Canadian Pat. No. 495,690 (Meuser) teaches that an H.sub.2 S-reactive iron oxide is produced during iron-mediated nitroaromatic reductions in the presence of both sulfuric acid and aluminum chloride. The iron oxide so produced is composed entirely of Fe.sub.2 O.sub.3 and in reaction with hydrogen sulfide, forms an unstable iron sulfide which regenerates H.sub.2 S upon acidification.
The foregoing methods appear to be effective only where the concentration of hydrogen sulfide is low, that is, not in excess of about 15 ppm. Further, all of these iron oxides in reaction with H.sub.2 S produce unstable products upon exposure to air or acids.